Newbie dumb questions

[MacAfrican]

I'm new to the Mac world and just downloaded SD (10.4.7 doesn't work so well with my Canon utilities and now I hear I should have gotten SD long ago...)

B4 I start, some basic tips please?

Q1: Can I use a second internal disk to backup/clone to? I know it's not a safe place, but thought it'd be fast and I will also backup to an external on longer cycles.
Q1A: If yes, should I set up a partition on my external disk and clone to that partition? My second disk already has stuff on it, but data only so not stuff that I'll need to do a system recovery.

Q2: would I be better off with two physically seperate firewire disks of say 250 each or one huge external firewire? I'd like to keep a weekly copy, a month-end copy and a copy of the month-end before that one (i.e 30 June, 31 May and a Sunday weekly)

Thank you, and I am am printing the manual to start reading. Promise